Method for producing acetylacetone



United States Patent METHOD FOR PRODUCING ACETYLACETONE Eduard Enk andFranz Biittner, Burghausen-Upper Bw varia, Germany, assignors toWacker-Chemie G. in. b. H., Munich, Germany, a German firm No Drawing.Application July 19, 1956, Serial No. 598,757

Claims priority, application Germany August 5, 1955 3 Claims. (Cl.260-595) The present invention relates to a method of producingacetylacetone.

It is known to transform isopropcnylacetate in the vapor phase at 500 C.into acetylacetone whereby the yield is about 45%. Acetone and ketene,which is decomposed, separating carbon, appear as lay-products. Theyield diminishes after a short time due to the formation of soot in thereaction chamber which also promotes undesired decompo-sition of theisopropenylacetate instead of transformation into acetylacetone.

We have found that the separation of carbon can be completely prevented,for all practical purposes, and that the amount of the producedacetylacetone can be considerably increased, if isopropenylacetate inthe vapor phase is brought in contact with metallic molybdenum as acatalyst at 300 C. to 600 C. It may be used finely dispersed on anindifferent carrier, for example pumice, whereby the amount ofmolybdenum may be varied within very wide limits; generally, 2 topercent, by weight, on the carrier are suflicient. The molybdenum may beused as the catalyst in the form of alloys, for example, amolybdenumdron alloy containing 1.8% to 10% molybdenum. The catalyst maybe in the form of balls, turnings, wire coils, and the like.

Example 1 The vapor of 200 grams isopropenylacetate was conducted perhour at 600 C. through a pipe of 600 mm. length and 34 mm. diameter andmade of refined steel, the pipe having been filled with 500 ccm.turnings consisting of molybdenum-iron alloy containing 2% by FatentedApr. 2, 1957 weight of molybdenum. The cooled gas exhausting from thepipe separated after three hours 560 grams liquid which wasfractionated. Aside from acetic acid and acetone, 390.2 gramsacetyl-acetone was obtained and 111 grams isopropenylacetate wasregained. This corresponds to a reaction of 65.2% and a yield of of thetheoretical yield with respect to acetylacetone. 10 grams acetic acidanhydride, corresponding to 4.1 grams ketene was obtained from thegaseous reaction products. The interior wall of the pipe or oven wasentirely free of soot after 21 hours of operation and the yield wasunchanged. The acetylacetone was 93% to 95% by weight after the firstdistillation and contained only one impurity, acetic acid, because itwas substantially free of ester and water. The so produced acetylacetonedissolved in 3-N aqueous ammonia, the solution being absolutely clear.

Example 2 The pipe described in Example 1 was filled with 500 ccm.pumice granules containing 10%, by weight, finely dispersed molybdenumand having a size of between 5 and 7 mm. The vapor of 600 gramsisopropenylacetate was conducted through the pipe during three hours ata temperature of 500 C. 553 grams liquid was obtained from the reactiongases by cooling, which liquid was fractionated. Thereby 299 grams pureacetylacetone and 151 grams isopropenylacetate, which did not react,were produced. This corresponds to a reaction of 50% and a yield of 67%with respect to acety-lacetone. The transformation continueduninterruptedly for more than 12 hours without any carbon deposits onthe catalyst and on the wall of the reaction chamber.

What is claimed is:

1. A method of producing acetylacetone by transformingisopropenylacetate in the vapor phase at a temperature between 300 C.and 600 C. in the presence of metallic molybdenum as a. catalyst.

2. A method as defined in claim 1 in which the catalyst consists of amolybdenum-iron alloy containing between 1.8% and 10% molybdenum.

3. A method as defined in claim 1 in which the molybdenum is finelydispersed on a carrier made of an indifferent material.

No references cited,

1. A METHOD OF PRODUCING ACETYLACETONE BY TRANSFORMINGISOPROPENYLACETATE IN THE VAPOR PHASE AT A TEMPERATURE BETWEEN 300* C.AND 600* C. IN THE PRESENCE OF METALLIC MOLYBDENUM AS A CATALYST.